Method of manufacturing a heating element



Patented Sept. 1, 1936 PATENT Flo's IHETHOD F MANUFACTURING A HEATING ELEMENT Leonard R. Blggs, Schenectady, N. ill, assignor to General Electric Company, a corporation at N cw York Application August 3d, 193%, Serial No. 742,13d

t tillaims.

The present invention relates to mercury boilers comprising containers and heating elements for heating and evaporating mercury liquid or like 'fluid, more specifically to the kind of boilers in which such heating elements form wall screens lining the walls of a furnace and protecting such walls against excessive heat in the combustion.

space.

One object of my invention is to provide an improved construction and arrangement of wall screen heating elements, and the principal object of myv invention is to provide an improved method of manufacturing wall screen heating elements. 1

For a consideration of what I believe to be novel and my invention, attention is directed to the following description and the claims appended thereto in connection with the accompanying drawing.

In the drawing, Fig. l is a diagrammatic view of 20. a mercury boiler embodying my invention; Fig. 2 is an enlarged sectional view along line 2-2 of Fig. 1; and Figs. 3 and 4 are perspective views of a heating element in different stages of manufacture. y The boiler shown in Figs. 1 and 2 comprises a furnace having a wall ill forming a combustion chamber ii. A drum it for containing mercury is supported on the wall it. The drum has a vapor discharge conduit is and is connected to a heating element is comprising a plurality of tubes and channel members l5 lining the inner surface of the wall iii and thereby protecting it against excessive heat in the combustion chamber. Mercury liquid is conducted to the lower ends of the channel members l5 through downtubes it which are disposed at least partly outside the furnace wall in. The upper ends of the down-tubes are connected to the drum i2 and the lower ends of these tubes are connected to the lower ends of the channel members i5. Each member I5 has a lower portion forming a plurality of channels I! (Fig. 2). In the present instance I have shown an arrangement in which the lower portion of each channel member i5 forms four cylindrical channels H. The walls of these channels are integrally united by a heavy foundation member l8 which on its side facing the combustion space is provided with refractory material [9. This material is held on projections 5 20 integrally formed on the foundation member IS. The upper ends of the channels II are connected to the drum l2 by individual tubes 2| (Fig. 1) welded to the walls of said channels. As shown in Fig. 2 the ends of adjacent elements I5 to overlap each other. whereby slag is prevented from entering the space defined between the furnace wall it and the heating elements it. No such overlapping arrangement is necessary with respect to the tubular extensions it because slag is mainly formed in the lower portion of the comit bustion space while tubes 20 are provided in an upper portion of the combustion space. The provision of wall screen elements which have lower portions made of solid, massive foundation plates with a plurality of parallel channels formed it in each plate permits the provision of mercury wall screen heating elements in the lower portion of mercury boilers of considerable height. With my invention it is no longer necessary to protect the walls in the lower portion of the combustion l5 space by means of wall screen heating elements containing water to be heated and evaporated. An important feature of my invention is the provision of the lower portions of the mercury wall screen heating elements with refractory material 20 it, as stated above, in order to protect these portions from excessive heat in the combustion space.

In manufacturing a lower portion or channel member 85 of a wall screen heating element, I 25 produce in accordance with my invention a block or foundation member from steel or like material and subject such foundation member to a rolling process. With the rolling process 1 form on one side of the foundation 'member a plurality of 30 parallel projections 25, 26 and simultaneously I form on the other side of the foundation member a plurality of other projections, preferably in the form of knobs 2t. Adjacent pairs of projections 25 and 26, as indicated in Fig. 3, form rounded 35 I recesses 28. The next step in the manufacture of such heating elements is to bend adjacent projections 25 and 26 so that their edges engage each other and their inner surfaces form a cylindrical channel. This step of my invention is indicated 4 in Fig. 4 where walls 29 and 30 have been bent towards each other and form a circular conduit. The outer edges of the walls 29 and 30 form a recess 3|. This recess in accordance with the next step of my invention is filled with fused 45 metal, preferably by a welding process, to firmly unite the walls 29 and 30, as indicated at 32.

I The heavy structure of the lower portion of the wall screen heating elements accomplished with my invention permitsheating of the mercury to high temperatures without endangering said lower portions or channel members of the heating elements. The substantially plane walls of said lower portions facilitate the provision of refractory material thereon. This material is securely 5 boilers. The elements according to my invention have flat surfaces exposed to the fire, which surfaces absorb the heat uniformly and at the same time form a perfect enclosure of the combustion space in furnaces. The heating elements, especially the lower portions thereof form a. plurality of round channels, or, from another viewpoint, a plurality of tubular members for receiving mercury to be heated. Thus the heating elements have all the advantages of round tubes. They require a, minimum amount of liquid and can withstand high boiler pressure. Hence, a heating element according to my invention comprises, viewed from another angle, a plurality of round tubes united to form a fiat surface.

Having described the method according to my invention, together with the apparatus ior carrying out the method, I wish to have it understood that changes may be made in both the apparatus and the method without departing from the spirit of my invention and the scope of the appended claims.

What I claim as new and. desire to secure by Letters Patent oi the United States, is:

l. The method of manufacturing a heating ele ment having a plurality of substantially parallel channels for containing a fluid to be heated, said method including the steps of subjecting a foundation member to a rolling process to form thereby a plurality of parallel walls on one side of the foundation member, and uniting adjacent walls to form channels.

2. The method of manufacturing a heating element having a plurality of substantially parallel channels for containing a fluid to-be heated, said method including the steps of subjecting a foundation member to a rolling process to form thereby a plurality of parallel walls on one side of the foundation member, bending adjacent walls in opposite directions, and uniting the edges of the bent walls by a welding process.

3. The method of manufacturing a heating element having a plurality of substantially parallel channels for containing fiuid to be heated, said method including the steps of subjecting a foundation member to a rolling process to form a plurality of parallel walls thereon with adjacent pairs of walls forming rounded recesses, bending the walls of each pair towards each other to form cylindrical channels, and integrally uniting the edges of each pair of walls.

4. The method of manufacturing a heating element having a plurality of substantially parallel channels for containing a fluid to be heated, said method comprising the steps of subjecting a block of steel to a rolling process to form a plurality of parallel walls on one side and projections'on the other side thereof, bending adjacent walls towards each other, and uniting the edges of the bent walls by welding.

LEONARD R. 81668. 

